1. Field of the Invention
The present invention relates to an insertable tool for an electrical machine, particularly a hand-held tool for drilling and/or impact operations, including a tool shaft that can be inserted into a respective tool holder of the machine, the shaft having means for rotary driving and axial locking. The invention also relates to a tool holder for the machine having a receiving sleeve and an impact bolt for the tool shaft of the insertable tool.
2. Prior Art
From German Patent Disclosure DE 43 17 273 A1, embodiments for improving the rotary driving of insertable tools are already known, in which, in addition to the rotary driving grooves on the tool shaft, rotary driving cleats are also disposed on the circumference of the shaft. Although this does increase the rotary driving face and thus reduces wear, nevertheless the core cross section of the shaft is still weakened by both the rotary driving grooves and locking troughs, so that in impact operation, the shock wave introduced into the tool shaft by the impact bolt of the machine is not optimally carried to the tool tip. Moreover, notching effects arise at the base of the rotary driving grooves, and under severe rotary stress or rebound impact if the chiseling tool is titled can lead to breakage of the shaft. Such embodiments are therefore adequately stable and wear-resistant only for lighter-weight machines and lighter-weight insertable tools.
Swiss Patent CH 429 630 also discloses an impact drill head as an insertable tool, mounted on the end of a drill rod linkage for large drilling tools. Its tool shaft is embodied as a splined shaft, but for axial locking a chord-like recess that weakens the core of the shaft is provided for receiving a locking body inserted at the drill head holder. Once again, this embodiment leads to weakening of the drill head and to an impairment of the shock waves during operation.